In casting, a mold release agent is applied to the surface of a mold for the purpose of suppressing welding between the mold and a product to improve mold release. Conventionally, many aqueous dilution type mold release agents have been used as the mold release agent. The mold release agent contains 95% or more of water, and a small content of an active ingredient exhibiting a mold release action. The aqueous dilution type mold release agent is used in a method of spraying a large amount of the mold release agent onto the mold to cool the mold, applying the large amount of the mold release agent to secure the necessary amount of the active ingredient, and forming a coated film on the surface of the mold. However, this use method has a problem that the amount of waste of the aqueous dilution type mold release agent is extremely increased.
On the other hand, in recent years, with an improvement in the internal cooling technique of a mold, the use of an oily mold release agent has been started. Since the oily mold release agent can provide an effect in a use amount much smaller than that of the aqueous dilution type mold release agent, the oily mold release agent has no problem of a waste treatment, which is a large advantage. Furthermore, since the mold is not quenched for each shot as with the aqueous dilution type mold release agent, the use of the oily mold release agent has also been confirmed to allow the life of the mold to be lengthened as an advantage. The following Patent Literatures 1 and 2 have been known as such an oily mold release agent.